A simplified approach to monitoring in vivo therapy prescription

The urea kinetic model has been used to individualize therapy prescription. Because the urea kinetic model is complex, the modeling approach to therapy monitoring is not widely practiced. Presented here is a simplified approach to therapy prescription monitoring that is based on the full-fledged urea kinetic model. A Kt/V-PCR domain map (K: clearance, t: time and V: volume of urea distribution; PCR: protein catabolic rate) has been developed with the predialysis urea nitrogen concentration on the abscissa and the post/pre dialysis urea concentration ratio on the ordinate. On this domain map, the therapy index Kt/V is represented by a family of horizontal lines and the PCR is represented by a family of curved lines. In this simplified approach, midweek measurements of the pre (C1) and post (C2) dialysis urea nitrogen concentrations are plotted on the domain map. The position of the plotted point allows one to read off the Kt/V index and the PCR to determine whether therapy index, diet, or both need to be modified.